Tee 165×152×27 vs WT 6X17.5
Tee 165×152×27 is an Tees (from UB) section from the UK Blue Book (SCI P363); WT 6X17.5 is the closest equivalent in the American AISC Shapes Database. They are close to interchangeable in bending: 92.8 cm³ against 93.57 cm³ of plastic modulus, a difference of 0.8%. WT 6X17.5 is the lighter of the two at 26 kg/m against 27 kg/m, a saving of 3.8% on steel weight. WT 6X17.5 is deeper, 158.8 mm against 155.1 mm, which matters where the floor zone is tight.
| Property | Tee 165×152×27 Tees (from UB) | WT 6X17.5 WT | Difference |
|---|---|---|---|
| Mass | 27 kg/m | 26 kg/m | +3.8% |
| Depth | 155.1 mm | 158.8 mm | -2.3% |
| Width | 166.9 mm | 166.6 mm | +0.2% |
| Web thickness | 7.9 mm | 7.6 mm | +3.9% |
| Flange thickness | 13.7 mm | 13.2 mm | +3.8% |
| Area | 34.4 cm² | 33.4 cm² | +3.0% |
| Second moment, major (Iy) | 642 cm⁴ | 666 cm⁴ | -3.6% |
| Plastic modulus, major (Wpl,y) | 92.8 cm³ | 93.57 cm³ | -0.8% |
| Elastic modulus, major (Wel,y) | 52.2 cm³ | 52.93 cm³ | -1.4% |
| Second moment, minor (Iz) | 531 cm⁴ | 507.8 cm⁴ | +4.6% |
| Plastic modulus, minor (Wpl,z) | 97.8 cm³ | 93.898 cm³ | +4.2% |
| Radius of gyration, minor (iz) | 3.93 cm | 3.91 cm | +0.5% |
| Torsion constant (It) | 17.3 cm⁴ | 15.36 cm⁴ | +12.6% |
Tee 165×152×27 to BS EN 10365:2017; WT 6X17.5 to AISC Shapes Database v16.0. Difference is expressed relative to WT 6X17.5.
How to choose between them
On stiffness, WT 6X17.5 has the larger second moment of area: 666 cm⁴ against 642 cm⁴, a difference of 3.6%. This matters more often than the strength comparison, because on normal floor spans deflection rather than bending capacity sets the beam size - so if the two are close on modulus but apart on inertia, the stiffer one is usually the better answer even when it is not the stronger one.
Measured as bending capacity per kilogram of steel, WT 6X17.5 is the more efficient section: 3.6 against 3.4 cm³ per kg/m, 4.5% better. Over a floor of repeated beams that difference is real tonnage, though it is often outweighed by whichever section the fabricator can actually source.
These come from different catalogues, so treat the swap as a design change rather than a like-for-like substitution. Tees (from UB) sections are specified to BS EN 10365:2017 and WT to AISC Shapes Database v16.0; the steel grades, tolerances and available lengths differ, connection details and bolt gauges are set out differently, and the two are rarely both stocked in the same market. Check availability before changing a section on a drawing to save 3.8% weight.
In short, WT 6X17.5 is the stronger section and WT 6X17.5 is the lighter one; where those are the same section, it is the clear choice, and where they are not, decide on whether your design is governed by capacity or by tonnage.